The insects commonly known as ladybugs or lady beetles (or ladybirds, in the UK and other English-speaking nations) include a number of species from the Coccinellidae family. Ladybugs are the subject of nursery rhymes and are considered a good luck symbol by many. For example, the seven-spot ladybird, the most common species in Europe, is said to represent the seven joys and seven sorrows. The ladybug is often considered a symbol of the Virgin Mary in Christian culture.
Like beloved native ladybugs, the Asian lady beetle (Harmonia axyridis) is a predator of a number of pest insects, especially aphids, but it has become a problem because it has overtaken native species. Asian lady beetles do not cause much damage to homes or home landscapes, but they often enter homes to seek warmth in cold weather. Once inside, the insects can crawl or fly around rooms and land on windows, walls, and furniture. Like other ladybugs, the Asian variety secretes a yellowish, smelly fluid if disturbed, which can stain walls, furniture, and fabrics.
Asian lady beetles are typically somewhat more aggressive than native varieties and may bite if they land on the skin. Though the bite is not very painful, contact can result in allergic reactions in some people. Effects can range from eye problems like conjunctivitis ("pink eye") to hay fever, cough, asthma, or hives. Reactions can be triggered by touching the lady beetles then touching your eyes, or just by being around a large or lengthy infestation of the insects.
3 Ways to Get Rid of Asian Lady Beetles
Asian lady beetles cannot be eradicated outdoors, and there's no point in trying to make your house less attractive to them when they've decided to seek shelter. But there are some simple methods for getting rid of those that make their way inside.
The simplest and most direct way to get rid of Asian lady beetles indoors is to suck them up with a vacuum. However, since the beetles secrete their stinky odor when distressed (and being sucked into a giant hose seems quite distressing), it's best to use a shop vac for this job, rather than your regular indoor vacuum. Seal and discard the vacuum bag after collecting beetles. To save on vacuum bags, you can also secure a nylon stocking around the exit end of the hose, using a rubber band. Remove the stocking immediately after turning off the vacuum, seal it closed with the rubber band or by knotting the end, and discard it.
Black light traps are effective for attracting and killing Asian lady beetles indoors, particularly in attics and other dark, enclosed areas. You can purchase traps suitable for this use or even make a DIY light trap using basic materials. Make sure the trap's light is the only light in the room so that beetles are attracted to it and not to other lights. Check and clean the trap regularly, especially when the infestation is heavy.
Various consumer-grade insecticide sprays are sold for killing Asian lady beetles. The same sprays are also likely to be effective for boxelder bugs, Japanese beetles, flies, cockroaches, ants, and other pest insects. Sprays are typically applied indoors or outdoors, in cracks and crevices, in storage areas, around window and door frames, and anywhere you find the beetles gathering. Asian lady beetles do not reproduce indoors, so you don't have to worry about targeting nests, as with ants. They may, however, return to the same place the next season.
Be Careful with Poisons
Follow the manufacturer's instructions carefully when applying insecticide, especially indoors and where children or pets may be present. Many beetle sprays are relatively mild but are still toxic.
Diagnosing and Dealing with Asian Beetles
What Causes Asian Lady Beetles?
Asian lady beetles spend the warmest months of the year in outdoor
feeding sites, including forests, wild and cultivated fields, and yards and
other landscaped areas. When the weather turns cool in autumn, they leave the
feeding areas in search of winter shelter. That’s how they end up in your home.
A few factors tend to stimulate this flight for shelter and attract beetles to specific sites:
- Swarms of migrating beetles tend to increase when the sun is out following relatively cool weather.
- Beetles fly most when temperatures are near 65 degrees Fahrenheit and above.
- Flight activity tends to be heaviest in the afternoon.
- Beetles are attracted to areas of contrasting light and dark, such as shaded corners of wall or roofs next to sun-exposed areas, or dark trim against a light background (or vice versa).
- Migrating beetles land on buildings then enter through cracks and crevices.
How to Prevent Asian Lady Beetles from Getting Into Your Home
The best way to control Asian lady beetles in your home is through pest-proofing measures to keep them from entering. These include sealing any cracks around windows, doors, utility wires, and pipes, and vents, as well as gaps or cracks in the siding, eaves, and foundation. It also is important to be sure that all doors and windows are tightly fitted and that screens are not torn or ripped. Insecticides applied around doors, windows, and other entry points (like cracks and crevices) can help keep beetles from entering the home. These must be applied before the beetles come into the home; they are not effective once the bugs are inside.
Gardeners seeking to introduce beneficial insects should take care not to purchase and distribute ladybugs from commercial sources because the ladybugs may be the Asian variety. While some "safe" species are sold, including Hippodamia convergens (convergent ladybug), Adalia bipuntata (red ladybug), and Coleomegilla maculata (spotted ladybug), these insects may have been harvested in the wild to offer for sale, which is a questionable practice.
A better strategy is to practice non-chemical gardening methods that encourage native ladybug species to visit your garden.
Asian vs. Native Lady Beetles
Ladybugs are not true bugs, but rather a group of some 6,000 types of small beetles that share a similarity in markings: orange or scarlet shells with black spots. These insects are more accurately called lady beetles. Most of the species are considered beneficial insects, since they feed on agricultural pests such as aphids and scale insects. Some species are natural predators of very serious pests such as the European corn borer.
The Asian lady beetle, the most prevalent North American ladybug, was introduced to the U.S. from Asia in 1916 to combat aphids. The USDA released the Asian lady beetles in Georgia, South Carolina, Louisiana, Mississippi, California, Washington, Pennsylvania, Connecticut, and Maryland, and the beetle has since then migrated throughout most of the United States. Along with this intentional introduction, it is likely the beetles reached the U.S. on freighters, adding to its presence throughout the country.
At a quick glance, it can be hard to tell the difference between the Asian ladybug and the native ladybugs, partly because the color of the Asian species can vary from light tan or orange to bright red, making them almost identical to some of the native species. But if you look closely, you will see the Asian ladybug has a white marking behind its head in the openings of what looks like a black "M." Some also have dark black spots, but on others, the spots are very light or nonexistent.
What Is Beetle Stain?
The so-called stain left by Asian lady beetles and other ladybugs is a small drop of yellowish liquid. It’s a secretion of volatile compounds emitted to fend off predators such as birds. The secretion has an unpleasant acrid odor.
Do Asian Lady Beetles Harm Plants?
Despite their invasive nature, Asian lady beetles do plants more good than harm. Their primary diet is aphids, which infest many garden plants and are among the most ubiquitous and persistent garden pests. They also feed on scale insects, another group of common garden pest.
Do Lady Beetles Carry Diseases?
Asian lady beetles are not known to carry diseases themselves and do not transmit diseases to humans. Because contact with beetles and/or their secretions may cause allergic reactions in sensitive individuals, it’s a good idea to wear gloves during contact with beetles and washing hands